He does not mention OS/2 around 1992. OS/2 included a VDM (virtual DOS machine) as standard to allow legacy apps to be run. It was about like IBM DOS v5.0. I remember playing Doom II in a VDM window on the OS/2 desktop.

You could install a copy of Windows (v3.1 at the time) onto this VDM or you could buy OS/2 with it already installed. At one point they (foolishly I think) referred to the latter version as "OS/2 for Windows" when it was really the other way round, but " xxxxxx for Windows" was a software selling point at the time.

It really was, as IBM said, a "better DOS than DOS and a better Windows than Windows" as DOS and Windows kept crashing at that time and in the VDM it was quicker to recover.

DOS may have crashed all the time but IBM DOS (other than the very first version) was actually produced by DR and not by MS; I always had DR-DOS rather than MS-DOS and I cannot recall it crashing at all.

It was only when I got round to Windows 98 in 2000 that I encountered an operating system that frequently crashed.

I did not think DR wrote IBM PC-DOS. I thought PC-DOS, as packaged with IBM PCs, was written by Microsoft, who also sold it separately (with some embellishments) as MS-DOS. Even then MS marketing had created a perception that they were the Gold Standard and I remember at work some guys wingeing bitterly that their corporate PCs came with PC-DOS and not MS-DOS.

In those days many PCs were sold with no operating system and DR stepped into this market (after some shaky starts) with DR-DOS, the "third way". DR-DOS was probably superior to the other two but MS deliberately put spoiler code in Windows 3.1 to prevent it being installed on DR-DOS [Look up "AARD Code" in Wikipedia].

DR-DOS was bought by Novell and then Caldera. I have Caldera DOS 7.01 on three floppies on my desk right now and I used to use it at home. It was free to non-commercial users.

If Windows 98 was the first OS you saw crashing you cannot have used Windows v3. Windows 3.0 was the first OS I used and it was truly awful - it would crash about once per hour with the dreaded UAE (Unrecoverable application error). It could not withstand an application crashing, but I think it always blamed the application anyway,

I'm not quite sure why IBM did not initially publicise that they obtained their version from DR - perhaps for marketing reasons; however, those who whinged at not getting MS-DOS obviously started a trend in whinging that they couldn't have the inferior MS product! Plus ça change ...

Yes having seen the appalling MS products in the 1980s, I decided to avoid MS if at all possible. Most people don't realise that, until Windows 95 when MS started 'giving away' what was to become MS Office, no one went out and bought MS office products - WordStar and then WordPerfect were the 'Gold standard' for word processors, Lotus 1-2-3 for spreadsheets and dBASE/Clipper/FoxPro for databases.

I was eventually forced to install Windows for an Open University course.